Grinder for mechanical pulp making

ABSTRACT

An improved grinder for mechanically making pulp from logs that has improved pulp-clearing passages associated with the grinding wheel and log-holding pocket.

United States Patent James H. Perry Worcester, Max.

June 2, 1970 Aug. 3, 1971 Norton Company Worcester, Mass.

Continuationdn-part of application Ser. No. 775,624, Nov. 14, 1968, now abandoned.

Inventor Appl. No. Filed Patented Assignee GRINDER FOR MECHANICAL PULP MAKING l0 Claims, 8 Drawing Figs.

Int. CL .t B02c 4/00, 802:: 4/44. B020 15/00 241/281 241/282 X 241/282 X 241/228 X 241/228 X [50] Field of Search 241/38, 46,

[56 References Cited UNITED STATES PATENTS 1,088,857 3/1914 Walters 1,342,231 6/1920 Schaanning 1,405,356 l/1922 Tidmarsh 2,642,231 6/1953 lllig 2,748,667 6/1956 Grieb 2,875,955 3/1959 Wendshuh Primary Examiner- Donald G. Kelly Attorney-Allan R. Redrow ABSTRACT: An improved grinder for mechanically making pulp from logs that has improved pulp-clearing passages associated with the grinding wheel and log-holding pocket.

PATENTEDAUB 315m 3,596,841

sum 1 [IF 2 JAMES 'w BE'RRY ATTORNEY cnmuan ron MECHANICAL PULPQMAKING CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my application Ser. No. 775,624 entitled "Ring Grinder for Mechanical Pulp Making, filed Nov. I4, 1968, and now abandoned.

BACKGROUND or THE INVENTION 1. Field of the Invention The invention relates to pulp-grinding machines and particularly to spaced log-guidingmeans and side pulp-clearing pockets for enhancing the efficiency of the pulp grinder.

2. Description of the Prior Art Various types of grinding machines have been developed for reducing a log to a pulp, it being desirable to separate the fibers from the log and from each other without breaking the individual fibers. Once conventional machine is a ring grinder, which is sometimes referred to as a Roberts grinder, wherein a large grinding wheel is rotated about a horizontal axis inside an eccentrically disposed rotatably driven ring. Logs are cut to a predetermined length approximately equal to the width of the grinding wheel surface and are fed horizontally into the wedgeor hom-shaped bight formed between the surface of the wheel and the external ring. The ring is disposed relative to the wheel such that the logs can be fed into'the wider upper portion of the horn-shaped pocketand the logs are moved by gravity downwardly to be directed by the converging wall of the ring to move against the surface oft'he grinding wheel with their longitudinal axes disposed generally parallel to the axis of the grinding wheel. Simultaneously the wheel and ring are driven to rotate in the same direction but at relatively much different speeds such that the grinding surface of the wheel in contact'with the logs moves in-a downwardly directionre'lative to the surface of the log whereby due to the gravityfeed, the motion-of theouter-ring and frictionalcontact with thewhee'l, the logs are positively driven into the constantly narrowing bight between the wheel and ring so thattheside facesor'surfaces of the logs are pressed againstthegrindingwheel with an appropriate degree ofpressure to accomplish fiber separation.

Flushing fluid is constantly suppliedin'thearea of the grinding'operation'to assist in the fiberseparation and removal. The fluid conditions the surface portion of the wood for fiber separation and also acts as a conveying medium to'carry the separated fibers to the 'outlet-of-the machine. The fluid conditions the woods surface, by penetrating into this portion of the log to soften the resins and lign ins which bond'the'fibers together. The shower :fluid also serves to prevent burning of the wood.

I In the operation of ring grinders heretofore,'the logs have SUMMARY or The INVENTION I have found that the efficiency of the grinding operation can'be considerably improved by spacing-the sidepIatesforming the'vertical walls of the pockets-slight distance'away from the'ends of the logs. It has heretofore "been-deemed necessary to'usesaid sideplates in close juxtaposition' to itheends o f the grinding wheel to hold'the logs in-place lengthwisein front of the-grinding surfaceso'thatallportions ofthe log-couldkbe'disintegrated] have speculated that suchclosepositioningof'the end guide-plates interfereswith removal of theshowerwater andthe fiber mixture produced and I have-found that spacing the sideplates away from the 'ends of'thelogsjgives the newly formed .pulp mixture and water :an -escape passage. The 'removalof Pulp raPidIy'from-thvzone \vhere'it-collectsat the ends of the logs after the pulp works over tothe end space, substantially speeds up pulp production and makes the grinding operation more efficient. In addition tomoving the plates away from the ends of the logs, I have found it desirable to provide spacers between the plates and the' ends of the logs that function to continue to center the logs with respect to the grinding surface ofthe wheel. I I V I In general the same grinding operation tak es place. in a socalled pocket grinder. The driven pulpstone is contained within a chamber having one or two pockets to receive logs to be ground. The pockets are filled with logs and pressure means force the logs against the surface of the pulpstone while water is showered over the moving wheel. The same process of pulp removal from the grinding zone can be accomplished by relieving the sidewalls of the log containing pockets, adjacent the periphery of the pulpstone so that pulp can work out to the end of the logs and fall downwardly to the pulp-receiving pit at the sides of and under the pulpstone. Suitable spacers cooperate with the ends of the logs to hold them centered in the pockets and the machine otherwise operates like. the ring grinder disclosed below.

BRIEFDESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional side elevation showing a ring grinder construction;

FIG. 2 is a top .plan view partly broken away showing the grinding machine and pocket of the ring grinder of FIG. 1;

FIG. 3 is a detail top plan viewof one of the sideplates of my invention;

FIG. 4 is aside elevation of the plate shown in FIG. 3;

FIG. 5 is a side elevation of a modified form of sideplate;

FIG. 6 is a sectional side elevation showing a typical pocket on one side of a pocketgrinder;

FIG. 7 is a view taken on line 7-7 of -FIG46; and

FIG. 8 is a detailed side elevation showing the spacer means for engaging the ends of the logs to hold the logs centered in the pocket while permitting the pulp to overflow into the pulpreceiving pit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred form of this invention is embodied in a ring grinder that has a conventional casing and support .means to contain the machine. A grinding wheel 10 is supported therein to be rotatably driven on a horizontally disposed drive shaft 1 L'The wheel is driven in the direction indicated by the arrow so that its active grinding surface is 'moving in a downwardly direction. A ring 12 having'an internal diameter substantially larger than the outer diameter of wheel 10 is 'eccentrically mounted with respect to the wheel, as shown,'to rotate about a "horizontaliaxis. The ring here shown has horizontal ribs on its under perip'heryand is driven :bysprocket chain .13 to rotate in the same directionas the wheel. The ring rotates at a much slower rate of r.p.m., however, the speed being usually in the range of about 240 r.p.m. for the wheel which is typically '62 inchesin diameter'while the ring is :rotated at a rate such that its surface moves forwardly at about '12 inches per minute.

The :ringhas an'inner diameterof'approximately 10 feet and is 'mounted'to be almost tangent'withthe wheel near the bottom of the grinder sothat'a horn-shaped grinding pocket is formed between the 'mner surfaceof-the :ringand'theouter surface of the wheels. The vertical sides of "the pocket are closed off by the 'sideplates'l4 that form the subject of this invention. The

side elevation of one such;plate is shown in FIG. 4.

Referring .to FIGS. .3 and 4, the 'preferred structure of a plate 14-is shown. Gne side'edge 'l5ofthe plate is shaped'to fit closely to and is generally concentrically arranged with respectto'the inner periphery of the ring 12, and the other side 16 of the plate is shaped to permit the sideplate to fit into the pocket with its edge 'lfifitted closely to the periphery of .thedrive Iflange on the grinding wheel. However, since the body of the plate is spaced laterally from the plane'in which ithe-en'o'f the grinding wheel with which it is associated rotates, the 'exact shape of theplate is not'too critical.

Referring to FIG. 2, it is apparent that the plates at opposite ends of the wheel are mirrorimages one of the other and on the inner surfaces of the plate 14 which are disposed at the opposite ends of the grinding pocket, a plurality of suitable vertically extending spacer ribs 17 are mounted. These ribs may take the form of solid bars welded to or cast or otherwise formed integral with the inner surfaces of the sideplates 14. l have found that ribs 1 inch square and spaced from 3 inches to 4"inches apart serve my purpose very well. The plates having such ribs formed thereon are adapted to be fixedly mounted at each end of the pocket in the ring grinder with the inner edges of the ribs at the opposite ends of the pocket substantially all aligned in the same planes in which the ends of the grindingwheel rotate respectively. The solid wall portions of the plates are thus disposed approximately l inch outside of these planes on the inner edges of the ribs as clearly shown in FIG. 2.

Either one or both sidewalls of the grinder may be provided with a suitable log-feeding opening 18 through which logs may be fed into the pocket horizontally to fall into the grinding pocket. The elements of the grinder are powered by suitable motors and conventional shower means 19 are provided to deliver fluids to the nip between the wheel and logs in the grinding zone. When the grinding pocket has been filled with logs and the relative rates of rotation of the wheel and ring have been established, the shower may be turned on and my machine is ready for operation.

As the grinding operation proceeds, the wheel engages the exposed sides of the logs in the grinding pocket. The ring 12 rotates slowly so that the logs are driven into the bight formed between the ring and the wheel to produce the desired grinding pressure required to reduce the logs to a pulp. The shower fluid interacts with mainly the surface portion of the log and the grinding wheel to condition the fibers at least several layers deep for removal from the log and the grinding action progresses continuously. As the fibers are separated from the log they combine with the flow of shower fluid intermixing with it to form a pulp, the mixture then in some manner migrates out of the grinding zone, by the path of least resistance. After it is initially formed by grinding contact between a wheel and a log, a substantial portion of the pulp mixture is carried along on the face of the wheel until the grinding surface of the wheel approaches the side of the next log that is being pressed against the wheel. This second log has intimate contact lengthwise along its side with the surface of the grinding wheel and the leading edge of this side of the second log tends to act like a scraper or doctor pressed against the wheel to remove the previously formed pulp. Because of the generally cylindrical shape of the logs and their random position in the pocket, there is always some space left between the logs to allow for the free passage of the mixture which can only escape by migrating to the ends of the logs to fall over the ends into the pit under the grinder. In the conventional ring grinder a large volume of the fiber and shower fluid mixture tends to accumulate between the logs and in the grinding pocket because its passage out of the pocket is restricted by the plates in contact with the ends of the logs, the plates forming the ends of the pockets. This accumulated volume of pulp mixture tends to interfere with the normal grinding action-by smearing or masking off the grinding surface of the wheel and thus reduces the grinding efficiency of the wheel. Grinding energy is wasted because some of it is used to churn the mixture and energy is lost in hydraulic shear.

In another fonn of my invention pulp flow passages are provided in a pocket grinder, thepassages being substantially tangent with the wheel at the periphery at the edge portion thereof. As shown in FIG. 6, a pocket 40 is provided to receive the logs to be ground and a driven piston 41 is adapted to be alternatively driven toward the grinding wheel to force the logs into contact with it and retracted from the wheel for loading the logs from infeed chamber 42 into pocket 40 when the door 43 is retracted with the piston. Such structure is well known and one or two pockets may be provided for feeding logs to the grinding zone. Suitable shower means and other normal grinder structure is provided.

Flow passages 44 for the pulp are provided on each side of the machine at the inner end of each of the pockets 40. The flow passages are generally vertically positioned at the opposite ends of the grinding wheel and are'spaced beyond the vertically disposed ends 45 of the cylindrical grinding wheel. The passages 44 communicate between the inner end of .the pocket where the logs are engaged by the grinding stone and the pit 46 below the machine which receives the pulp.

Log-engaging bars 50 are fixedly positioned to extend across the entrance way to each flow passage, the bars serving to center the logs in the pocket so they may be fed forwardly into engagement with the surface of the grinding wheel. The log-engaging sides 51 of the generally vertically disposed bars are preferably tapered in a direction to engage the ends forwardly moving the logs and drive any misplaced logs into a central position between the bars mounted in the oppositely disposed entrance ways as the logs are driven forwardly. The tips of the tapered faces of the bars 50 all lie substantially in the planes of the ends of the grinding wheel so that the logs are positioned to be ground to a pulp on the periphery of the pulpstone.

A number of bars 50 may be integrally mounted together with horizontal elements 52 to form a frame that may be mounted as a unit in the entrance way to each flow passage. The frame structure may be bolted in position on any fixed element of the machine.

Suitable doors 53 may be provided on each outer side of the flow passage 44 if desired, to permit inspection of the pulp being produced and make it possible to observe the grinding process.

In using my invention in either a ring grinder or a pocket grinder the fibers are separated from a given log and the shower fluid and fiber intermix to form the pulp. However, from this point on the pulp handling action is different from conventional grinders in that the pulp mixture is able to easily move laterally in the voids or spaces between the logs. The mixture of shower fluid and fibers collecting in such spaces due to the continuous grinding by the wheel,-forces the previously formed pulp outwardly toward the ends of the logs in a more or less continuous stream. In my machine the effect of this pumping action from behind together with the flow of shower fluid, causes the pulp mixture to work outwardly in both directions and flow over the ends of the logs adjacent the end plates 14 in the ring grinder or pocket grinder bars 50. The pulp then flows away from the logs into the spaces between ribs 17 or bars 50. The weight of the pulp mixture together with the motion of the flow which is imparted thereto by the rotation of the grinding wheel causes it to flow rapidly downwardly to the pit of the machine from which it may be removed. Due to the provision of the channels at the ends of the'logs for the free flow of pulp away from the grinding pocket, the pulp does not tend to accumulate in the grinding pocket as it has in the past, and a much faster removal of the shower fluids and fibers from the grinding zone is'accomplished. The elimination of collected pulp from the grinding pocket minimizes the smearing and masking actions believed to be inherent in previously known grinders.

In any event, it has been noted that by allowing the free passage of the pulp mixture out of the grinding pocket by way of the passages formed between the ribs, power economies have been effected. Also due to the more constant flow of the large volume of pulp mixtures, fluctuations in temperature throughout the grinder are minimized whereby a pulp having a more uniform quality is produced. This last factor can also be more precisely controlled with the improved control of pulp mixture flow from the grinding pocket because the best use can be made of the proper flow of shower water through the grinding zone, as will be well understood by those skilled in theart.

In some ring grinder machines, to obtain the improved results described above, it may be necessary to use differently constructed sideplates which are mirror images, one of which is shown in FIG. 5. Where it is impractical to mount a unitary plate along each side of the grinding wheel and ring, a split sideplate 30 can be used. in this instance the two parts Stand 32 of each of the plates 30 are fixedly mounted together within the machine adjacent the ends of the grinding wheel to perform the same function as the unitary plate structures 14. The two parts 31 and 32 are joined along their approximate midpoint at joint 34. Such composite structure is sometimes needed due to structural limitations in mounting the sideplates in different ring grinder machines.

I have found that a further improvement in the operation of my invention particularly in a ring grinder can be realized by designing the ribs f the composite plate structure to have a difi'erent angular relationship as shown in FIG. as compared with the rib design used on the unitary plate of FIG. 4. It will be noted that the ribs 35 formed on the upper section 31 of my composite plate extend substantially vertically along the inner side of the upper portion of composite plate 30 that is adapted to contact the ends of the log. The bottom section 32 has ribs 36 that are disposed slightly off the vertical. In the view shown in FIG. 5 the upper end of each rib 36 coincides with the bottom end of each rib 35 to provide a smooth continuation of the flow passage for the pulp mixture when it flows from the upper side of the grinding pocket downwardly toward the pit.

All of the ribs 36 on bottom section 32 are parallel but the bot-' tom ends are moved over slightly toward the grinding wheel, and I believe that when the pulp mixture flows away from the space between the logs at the ends of the logs in contact with the lower plate 32, that the natural flow line will impel the pulp mixture in the direction of the ribs 36. The pulling action of the edge portion of the wheel against the mass of the pulp mixture falling into the channels between ribs 36 where the edge of the wheel can contact such mixture tends to throw the pulp mix tangentially away from the wheel and the slight tuming of the flow passages to accommodate this change in direction of pulp flow enhances the removal of the pulp mixture from the grinding pocket. Since the plate 30 is made in two sections, the change in rib direction is easily accomplished as compared with duplicating this rib design in a unitary plate structure except by a casting procedure.

The operation of the plates shown in either FIG. 4, FIG. 5, or FIG. 8 is apparent from the description given above. Their use results in a power saving and production of a better quality of pulp. It is possible that modifications thereof may occur to those skilled in the art, which will fall within the scope of the following claims.

What I claim is:

l. A grinder including a driven cylindrical wheel and including pocket means to receive logs to be pressed against the wheel, a means to substantially cover the periphery of the I wheel with fluid a a point ahead of the junction the wheel forms with the logs in the pocket means, and pit means to receive the pulp produced in the machine characterized in that the pocket means has sidewalls for engaging the ends of the logs for holding the logs in position to be forced under pressure against the periphery of the wheel, said sidewalls having pulp flow passages lengthwise thereof directed generally in a parallel relationship to a tangent to the periphery of the wheel, said passages being open throughout their length to said pocket means to receive pulp in the form of fibers liberated from the logs and fluid mixed therewith, said flow passages connecting the area where the ends of the logs engage the sidewalls with the pulp-collec ting pit of the machine.

2. A sidewall for each side of the pocket of the grinder described in claim 1 wherein the grinding wheel is cylindrical and is driven to rotate about a horizontal axis, and each of said sidewalls are vertically disposed in planes substantially coextensive with the planes in which the ends of the cylindrical wheel rotate.

3. Sidewalls as defined in claim 2 wherein said pulp flow passages that are each exposed throughout their length in the pocket, are disposed between rigidly mounted bars that engage the ends of logs moving past the passages; said bars holding the logs centered in the pocket while permitting the pulp and fluidto enter the passa es to move to the collecting pit.

. A ring grinder accor mg to claim 1, including a driven cylindrical grinding wheel and a driven cylindrical ring having an internal diameter that is substantially larger than the diameter of the wheel, said wheel and ring being eccentrically mounted with respect to the wheel inside of the ring to be driven so that their ends rotate in substantially the same vertical planes, said wheel and ring rotating about their axes a relatively different speeds, the surface of said wheel and the internal surface of said ring forming a horn-shaped pocket to receive logs to be ground on the wheel to form a pulp, and said sidewalls for engaging the ends of the logs being positioned at each end of said horn-shaped pocket for holding the logs in position to be forced under pressure against the periphery of the wheel.

5. A sidewall structure according to claim 4 comprising a roughly horn-shaped vertically disposed sidewall at each end of said pocket, each of said hem-shaped sidewalls having a plurality of inwardly facing generally vertically disposed ribs on its side facing the pocket.

6. The structure of claim 5 wherein the edges of said ribs facing the pocket on the opposite sidewalls lie substantially in said vertical planes in which the ends of the wheel rotate.

7.' The structure of claim 5 wherein the ribs are l inch square in cross section and are spaced from 3 to 4 inches apart.

8. The structure of claim 4 wherein each of said sidewalls is a two-part plate divided generally horizontally at the midpoint, the flow passages in one part of each plate communicating with the flow passages in the other part of each plate.

9. The structure of claim 8 wherein said two-part plates each form a composite roughly horn-shaped vertically disposed wall at each end of said pocket having an upper and bottom part, each of said walls having a plurality of inwardly facing generally vertically disposed ribs on its side facing the pocket.

10. The structure of claim 9 wherein the bottom end of each of the ribs on the upper part of each of the composite plates is adapted to be aligned with the upper end of each of the ribs on the lower part where said ribs are joinedat the division lines separating the two parts of each of the plates. 

2. A sidewall for each side of the pocket of the grinder described in claim 1 wherein the grinding wheel is cylindrical and is driven to rotate about a horizontal axis, and each of said sidewalls are vertically disposed in planes substantially coextensive with the planes in which the ends of the cylindrical wheel rotate.
 3. Sidewalls as defined in claim 2 wherein said pulp flow passages that are each exposed throughout their length in the pocket, are disposed between rigidly mounted bars that engage the ends of logs moving past the passages; said bars holding the logs centered in the pocket while permitting the pulp and fluid to enter the passages to move to the collecting pit.
 4. A ring grinder according to claim 1, including a driven cylindrical grinding wheel and a driven cylindrical ring having an internal diameter that is substantially larger than the diameter of the wheel, said wheel and ring being eccentrically mounted with respect to the wheel inside of the ring to be driven so that their ends rotate in substantially the same vertical planes, said wheel and ring rotating about their axes a relatively different speeds, the surface of said wheel and the internal surface of said ring forming a horn-shaped pocket to receive logs to be ground on the wheel to form a pulp, and said sidewalls for engaging the ends of the logs being positioned at each end of said horn-shaped pocket for holding the logs in position to be forced under pressure against the periphery of the wheel.
 5. A sidewall structure according to claim 4 comprising a roughly horn-shaped vertically disposed sidewall at each end of said pocket, each of said horn-shaped sidewalls having a plurality of inwardly facing generally vertically disposed ribs on its side facing the pocket.
 6. The structure of claim 5 wherein the edges of said ribs facing the pocket on the opposite sidewalls lie substantially in said vertical planes in which the ends of the wheel rotate.
 7. The structure of claim 5 wherein the ribs are 1 inch square in cross section and are spaced from 3 to 4 inches apart.
 8. The structure of claim 4 wherein each of said sidewalls is a two-part plate divided generally horizontally at the midpoint, the flow passages in one part of each plate communicating with the flow passages in the other part of each plate.
 9. The structure of claim 8 wherein said two-part plates each form a composite roughly horn-shaped vertically disposed wall at each end of said pocket having an upper and bottom part, each of said walls having a plurality of inwardly facing generally vertically disposed ribs on its side facing the pocket.
 10. The structure of claim 9 wherein the bottom end of each of the ribs on the upper part of eaCh of the composite plates is adapted to be aligned with the upper end of each of the ribs on the lower part where said ribs are joined at the division lines separating the two parts of each of the plates. 